Climate change and civilizational collapse

Climate change and civilizational collapse refers to a hypothetical risk of the impacts of climate change reducing global socioeconomic complexity to the point complex human civilization effectively ends around the world, with humanity reduced to a less developed state. This hypothetical risk is typically associated with the idea of a massive reduction of human population caused by the direct and indirect impacts of climate change, and often, it is also associated with a permanent reduction of the Earth's carrying capacity. Finally, it is sometimes suggested that a civilizational collapse caused by climate change would soon be followed by human extinction.

Some researchers connect historical examples of societal collapse with adverse changes in local and/or global weather patterns. In particular, the 4.2-kiloyear event, a millennial-scale megadrought which took place in Africa and Asia between 5,000 and 4,000 years ago, has been linked with the collapse of the Old Kingdom in Egypt, the Akkadian Empire in Mesopotamia, the Liangzhu culture in the lower Yangtze River area and the Indus Valley Civilization.^[2][3] In Europe, the General Crisis of the Seventeenth Century, which was defined by events such as crop failure and the Thirty Years' War, took place during the Little Ice Age. In 2011, a general connection was proposed between adverse climate variations and long-term societal crises during the preindustrial times.^[4] However, all of these events were limited to individual human societies: a collapse of the entire human civilization would be historically unprecedented.

Some of the more extreme warnings of civilizational collapse caused by climate change, such as a claim that civilization is highly likely to end by 2050, have attracted strong rebutals from scientists.^[5][6] The 2022 IPCC Sixth Assessment Report projects that human population would be in a range between 8.5 billion and 11 billion people by 2050. By the year 2100, the median population projection is at 11 billion people, while the maximum population projection is close to 16 billion people. The lowest projection for 2100 is around 7 billion, and this decline from present levels is primarily attributed to "rapid development and investment in education", with those projections associated with some of the highest levels of economic growth.^[7] However, a minority^{[citation needed]} of climate scientists have argued that higher levels of warming—between about 3 °C (5.4 °F) to 5 °C (9.0 °F) over preindustrial temperatures—may be incompatible with civilization, or that the lives of several billion people could no longer be sustained in such a world.^{[8][9][10][11]} In 2022, they have called for a so-called "climate endgame" research agenda into the probability of these risks, which had attracted significant media attention and some scientific controversy.^[12][13][14]

Some of the most high-profile writing on climate change and civilizational collapse has been written by non-scientists. Notable examples include "The Uninhabitable Earth"^[15] by David Wallace-Wells and "What if we stopped pretending?" by Jonathan Franzen,^[16] which were both criticized for scientific inaccuracy.^[17][18] Climate change in popular culture is commonly represented in a highly exaggerated manner as well. Opinion polling has provided evidence that people across the world believe that the outcomes of civilizational collapse or human extinction are much more likely than the scientists believe them to be.^[19][20]